The current study presents the most detailed multigene phylogenetic assessment of the red algal family Kallymeniaceae to date emphasising the floras of Australia (220 specimens), Europe (19 specimens) and North America (54 specimens). Toward a natural classification and in light of our phylogenetic results, we propose numerous taxonomic changes including the recognition of ten new genera: Austrokallymenia Huisman & G.W.Saunders; Glaphyrymeniopsis Kraft & G.W.Saunders; Huonia G.W.Saunders; Leiomenia Huisman & G.W.Saunders; Metacallophyllis A.Vergés & L.Le Gall; Nothokallymenia A.Vergés & L.Le Gall; Rhipidomenia G.W.Saunders; Thalassiodianthus G.W.Saunders & Kraft; Tytthomenia G.W.Saunders; and Verlaquea L.Le Gall & A.Vergés. The proposals of new genera are accompanied by 16 new combinations of which half are for species from the formerly species-rich genus Kallymenia. Approximately 50 undescribed genetic species were uncovered, of which only ten are now formally named, five of which are type species for new genera: Glaphyrymeniopsis mollis Kraft & G.W.Saunders, Huonia sandersonii G.W.Saunders, Leiomenia lacunata Huisman & G.W.Saunders, Thalassiodianthus incrassatus G.W.Saunders & Kraft and Tytthomenia barrettii G.W.Saunders. The remaining five are Austrokallymenia rebeccae G.W.Saunders & Kraft, A. roensis Huisman & G.W.Saunders, Leiomenia imbricata Huisman & G.W.Saunders, Meredithia compaginata G.W.Saunders, and Verlaquea fimbriata G.W.Saunders. Also described and illustrated for the first time are reproductive features of the northeastern-Pacific Euthora timburtonii Clarkston & G.W.Saunders, which has been known until now only from molecular studies of vegetative thalli. Despite advances made by our work, the need for considerably more taxonomic investigation in this diverse family is demonstrated, particularly within the presently constituted genus Callophyllis.

Cystoseira granulata C. Agardh var. turneri Montagne was described by Montagne (1838) from Algeria (southern Mediterranean Sea). Subsequently, Agardh (1842) renamed the taxon as C. montagnei J. Agardh, on the basis of specimens from France and the northern Adriatic (northern Mediterranean Sea) which he believed to be identical to Montagne's taxon. Finally, Sauvageau (1912) described C. spinosa Sauvageau and C. adriatica Sauvageau as nomina nova, to partly accommodate Agardh's and some other authors' concept of C. montagnei. These taxonomic treatments caused confusion regarding the delineation of these taxa and doubts have been raised regarding the taxonomic value of Montagne's taxon, which today is often listed as taxon inquirendum in updated checklists and floras. Since 2014, we have collected near Algiers (Algeria) a species of Cystoseira that formed sparse forests between 10 and 25 m depth. Our specimens perfectly match the original description as well as the syntype material of Montagne's taxon. They are well characterized and distinct from C. montagnei J. Agardh and from all the Cystoseira taxa hitherto described in having: a single axis with young tophules spinose becoming smooth-tuberculate when older; primary branches either slightly compressed with an inconspicuous rib and irregularly alternate in one plane, or cylindrical and branched in all directions, with spaced short spine-like appendages; and conceptacles both intercalary basal, just above the tophule, and terminal on branchlets. Here, we propose Cystoseira michaelae Verlaque et al. nom. et stat. nov. to accommodate Montagne's taxon (Cystoseira granulata C. Agardh var. turneri Montagne) and the lectotypification of the species on the basis of both Montagne's protologue and of an original specimen of Montagne (out of the syntype housed at the Muséum National d'Histoire Naturelle de Paris, PC). Cystoseira michaelae seems to be an endemic species restricted to Algeria and northern Tunisia. In addition, C. montagnei J. Agardh is lectotypified on the basis of an original specimen of J.G. Agardh (out of the syntype housed at the Botanical Museum of Lund University, LD). The study of lectotypes of C. spinosa Sauvageau and of its synonym C. adriatica Sauvageau confirmed that they are junior synonyms of C. montagnei J. Agardh.

Based on samples collected from two mountain lakes named as Lacs Paponoun located in the Cameroon Highlands (Africa), an assemblage of chrysophycean stomatocysts was investigated using scanning electron microscopy. Twenty stomatocysts are reported and described following the guidelines of the International Statospore Working Group (ISWG). Eleven cysts are described as new morphotypes. The present study documents the largest assemblage of chrysophycean stomatocysts from the recent sediments in tropical Africa detected so far. Additionally, it provides new data on global diversity of chrysophycean stomatocysts.